Mayor Bloomberg marching in the St. Patrick's Day parade today.brigitte stelzer

Some Celts are still cross.

Boos followed Mayor Bloomberg yesterday as he walked in the annual St. Patrick’s Parade in Rockaway, Queens — his first Irish outing since he made a quip about their drinking last month.

Many in the working-class neighborhood also got their Irish up over Bloomberg’s cost-cutting initiatives, including his efforts to overhaul the city pension system, fire more than 4,000 teachers, and change the “last in, first out” rule for teacher layoffs.

“Go back to Manhattan!” yelled several parade-goers as Bloomberg and other elected officials strolled the 30-block route along Newport Avenue and Rockaway Beach Boulevard in Belle Harbor.

Chants of “Union-buster!” and “Respect the teachers!” trailed after Bloomberg, who was making his 10th consecutive appearance at the parade.

Maureen Bergin, one of about 6,000 proud sons and daughters of Erin lining the march, said Bloomberg disrespected her heritage when he joked that he usually only saw “people that are totally inebriated” at the Irish American Historical Society on Fifth Avenue.

“He wouldn’t have the audacity to make that joke about another group of people,” grumbled Bergin. “Plus, I’m a teacher, so he’s not on my list of favorite people right now.”

Retired worker Ellen Moran agreed. “A stereotype is simply a stereotype. It may have been a joke, but the bottom line is, I was offended.”

Anthony Hannon, 80, was more angered by Bloomberg’s quality of life initiatives – like outlawing smoking in public places such as the boardwalk on Rockaway beach.